How do you preview a specific sites page as Admin?

I have a sites page that is not part of the navigation that I would like to preview in Admin mode. How do I preview that specifc page in Admin mode.

Right now I am getting an Authorization Required message which is not very useful for debugging purposes. I have tried logging the public user but even then the logs don't tell me which field or script etc... that the public user does not have access to that is generating the run time error.

Maybe my default behavior for Preview as Admin is doing something different than what should be happening. I don't see a list of all site pages when clicking preview as admin it just redirects to a page.

I tried using the debug log on the public sites user however it does not give any detail as to what is causing the Authorization Required message. I have a very strong feeling that it is related to a view permission that is lacking in one of the objects that the page is attempting to access.

I tried replacing the internal VF page code with a text string and still getting the error which must mean something in the custom controller I am calling (which the Site user has permission to see) must be doing something that the Sites user is not permitted to access.

I had a similar symptom which turned out to be DML that I was trying to run in the constructor, however that is not the problem that is happening here. So I am trying to figure out what I can do to get more clarity on the issue since Debug Logs and viewing the Visual Force pages directly don't shed any light on the problem.

So thats kind of where I am at. I probably should be posting my controller code, but really want to know how to debug this issue better as I seem to experience trouble with permissions when creating Sites pages often.